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what you are doing there will require 3 biquads. if that was your aim, this way it will of course work to design a filter.
yet you are still ending up with a series of filters of the known standard types. :)

how to use a linear knob or fader to control poles and zeros? no idea.

i think to find musically interesting settings you can stick to using multiple filtergraphs … the zplane isnt really giving you access to something useful.